Laser marks are inscribed on IC components such as Arabic numerals, English letters, symbols, and trademarks to easily distinguish the device types, lot numbers, fabricator and fabricated locations of IC components. A chip with laser mark is revealed in R.O.C. Taiwan patent publication No. 395,041. A plurality of transistors are fabricated on the primary surface of the chip, and a laser marks is formed on the second surface of the chip to identify the chip.
Generally, laser marks are inscribed by a laser beam with a small beam diameter. The beam diameter of a laser beam is quite smaller than the stroke width of the laser mark. Therefore, multiple laser paths in parallel are gathered as a character stroke for recognition.
As shown in FIG. 1, a conventional laser mark 100 in an IC component comprises a plurality of characters 110 which may be upper or lower case English characters or Arabic numbers. Each character 110 has at least a character stroke, the character stroke width 111 much greater than the width of a laser path 120 by a laser beam. As a result, a laser beam needs to repeatedly open and close from one end of the character stroke to another end of the character stroke to form a plurality of laser paths 120 in parallel as a character stroke. Each laser path 120 is individually created by inscribing of a laser beam to have two endpoints 121,122. Because the endpoints 121 or 122 of the laser paths 120 in a same character stroke are adjacent, end-to-end breaks apparently look like a defect (as shown in upper photograph in FIG. 3). When the character 110 is an Unclosed character such as “C”, “h”, “M”, “S”, . . . etc., the first endpoints 121 and the second endpoints 122 of the laser paths 120 are numerous and respectively located at two ends of the character stroke leading to discontinuity and broken lines of an character 110. When the character 110 is a closed character such as “O”, “0”, all of the first endpoints 121 and the second endpoints 122 of the laser paths 120 in the closed character are close together to from an obvious gap. The gap should be kept, otherwise overlapping will lead to over-inscribing and causes melting and diffusion on the back surface of an IC component. Therefore, lots of endpoints 121 and 122 of the laser paths 120 are separate and adjacent causing discontinuity and broken lines between the laser paths 120.